1. Field of the Invention
The present invention relates to a communication system for implementing maintenance of a copying machine, and more particularly to a communication system which operates to connect a copying terminal provided with a copying machine on the side of a user with a host computer installed in a service station.
2. Description of the Related Art
As far as the inventors of the present application know, the currently available copying machine counts a total number of copied sheets and a number of jammed sheets and uses them as a criterion for the maintenance. To read such count values, a maintenance personnel routinely calls at the user's office and handles an operation panel provided normally on the top of the copying machine body. This routine work takes too much time and is so costly, because it needs the maintenance personnel to do the routine visit to the user's office. To overcome these shortcomings, in recent days, the inventors of the present application know that a communication system has been studied where the read/write of data is carried out in a host computer installed in a service station through a phone line for automating and saving the time and labor of count reading and billing operations. Through this communication system, the maintenance data such as the total count values are routinely transmitted to the host computer so that the maintenance personnel may not need to visit the user's office for reading those count values. The maintenance time is determined on the data sent from the user's office.
However, disadvantageously to this system, each copying machine may have its own settings such as a maintenance period (defined depending on a predetermined time or count value) and some other communication conditions of its service station. The known communication system has predetermined communication settings such as a data transfer period. For example, when the copied sheet (count value) reaches 1000, the count value is sent to the host computer. As such, the known communication system provides no capability of doing data transmission according to the kind of the copying machine or the maintenance policy of each maintenance personnel.
As another disadvantage, the known communication system is arranged so that a plurality of copying terminals are connected to the host computer through the communication line. If, for example, the two pieces of maintenance data sent from the two copying terminals collide with each other on the communication line, the data transmission is jammed. To overcome this jamming, each copying terminal provides a timer so that the transmitting time of one copying terminal is shifted from that of another copying terminal for preventing collision of the data transmission timings. However, if a time lag takes place in the timer of each copying terminal, the data collision may be brought about though the actual transmitting times are set differently.